cfg80211: remove double prototype

cfg80211_calculate_bitrate() is defined in the external
header file cfg80211.h now, so no need to keep it in
the internal one as well.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/wireless/core.h

@@ -445,8 +445,6 @@ int cfg80211_set_freq(struct cfg80211_registered_device *rdev,
 		      struct wireless_dev *wdev, int freq,
 		      enum nl80211_channel_type channel_type);
 
-u16 cfg80211_calculate_bitrate(struct rate_info *rate);
-
 int ieee80211_get_ratemask(struct ieee80211_supported_band *sband,
 			   const u8 *rates, unsigned int n_rates,
 			   u32 *mask);